Add Enterprise-User group opt-in for Extensions Marketplace
## Description Let's equip groups that manage [Enterprise Users](https://docs.gitlab.com/ee/user/enterprise_user/) to opt-in to the extensions marketplace. This setting will be disabled by default, but we'll have instructions in the Web IDE UI for how to enable. ## Context See [this thread](https://gitlab.com/groups/gitlab-org/-/epics/14421#note_1993440122) for more context: > With this option, we might be able to satisfy our customer's governance requirements more iteratively. Can we assume that `.com` customer's wanting this level of extensions marketplace control are utilizing the [Enterprise User](https://docs.gitlab.com/ee/user/enterprise_user/) feature? If so, then we can utilize this relationship between User/Group and introduce a simple `allow_enterprise_user_extensions_marketplace` flag that will affect **all** Web IDE visits. ## Implementation Plan 1. Add `enterprise_users_extensions_marketplace_opt_in` db field for group. This should have some symmetry to the field we use in the user preferences side. 1. Update logic in [`metadata_for_user`](https://gitlab.com/gitlab-org/gitlab/-/blob/c390bb705d121ffed968516282766ec19768d123/lib/web_ide/settings/extensions_gallery_metadata_generator.rb#L46) to respect the Enterprise Group's setting. This is also an EE concern. 1. Update Web IDE to show helpful error message when the disabled reason is caused by the user's enterprise group. 1. Add UI for this in Group Settings.
epic